A terminal apparatus communicates with a base station apparatus by using a plurality of cells including at least a primary cell and a secondary cell. The terminal apparatus decodes a PDCCH with downlink control information format in which at least a transmission power control command field is included, transmits a PUCCH on the primary cell, and determines transmission power of the PUCCH on the primary cell based on at least a PUCCH power control adjustment parameter. The PUCCH power control adjustment parameter is calculated by accumulating at least a value indicated by the transmission power control command field, and in a case where the terminal apparatus receives a random access response message for the primary cell, the transmission power control circuitry is configured to and/or programmed to reset the PUCCH power control adjustment parameter.